Just to share in case someone else comes across this.
I normally has 12 GA. solid core cable going to my speakers and my sub from the Amp terminals.
Due to the 12 GA. thickness it is difficult to keep everything together at the terminals. I decided to replace the sub connects with 18 GA. wire. The stage vanished, flat harsh sound came out…Stark difference.
I replaced the original 12 GA. Cable and everything came back.
I don’t know how this can happen when the 18 GA. never even touched the speakers, but it certainly did.
Any thoughts on what caused this?